1 /*
2  * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <stdlib.h>
18 #include <string.h>
19 
20 #include "telescope.h"
21 #include "utf8.h"
22 
23 /*
24  * Text wrapping
25  * =============
26  *
27  * There's a simple text wrapping algorithm.
28  *
29  * 1. if it's a line in a pre-formatted block:
30  *    a. hard wrap.
31  *    b. repeat
32  * 2. otherwise advance the line char by char.
33  * 3. when ending the space, split the line at the last occurrence of
34  *    a "word separator" (i.e. " \t-") or at point if none.
35  * 4. repeat
36  *
37  */
38 
39 void
40 erase_buffer(struct buffer *buffer)
41 {
42 	empty_vlist(buffer);
43 	empty_linelist(buffer);
44 }
45 
46 void
47 empty_linelist(struct buffer *buffer)
48 {
49 	struct line *l, *lt;
50 
51 	TAILQ_FOREACH_SAFE(l, &buffer->page.head, lines, lt) {
52 		TAILQ_REMOVE(&buffer->page.head, l, lines);
53 		free(l->line);
54 
55 		if (l->type != LINE_COMPL &&
56 		    l->type != LINE_COMPL_CURRENT)
57 			free(l->meta.alt);
58 
59 		free(l);
60 	}
61 }
62 
63 void
64 empty_vlist(struct buffer *buffer)
65 {
66 	struct vline *vl, *t;
67 
68 	buffer->top_line = NULL;
69 	buffer->line_off = 0;
70 	buffer->current_line = NULL;
71 	buffer->line_max = 0;
72 
73 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
74 		TAILQ_REMOVE(&buffer->head, vl, vlines);
75 		free(vl->line);
76 		free(vl);
77 	}
78 }
79 
80 static int
81 push_line(struct buffer *buffer, struct line *l, const char *buf, size_t len, int flags)
82 {
83 	struct vline *vl;
84 
85 	if (!(l->flags & L_HIDDEN))
86 		buffer->line_max++;
87 
88 	if ((vl = calloc(1, sizeof(*vl))) == NULL)
89 		return 0;
90 
91 	if (len != 0 && (vl->line = calloc(1, len+1)) == NULL) {
92 		free(vl);
93 		return 0;
94 	}
95 
96 	vl->parent = l;
97 	if (len != 0)
98 		memcpy(vl->line, buf, len);
99 	vl->flags = flags;
100 
101 	if (TAILQ_EMPTY(&buffer->head))
102 		TAILQ_INSERT_HEAD(&buffer->head, vl, vlines);
103 	else
104 		TAILQ_INSERT_TAIL(&buffer->head, vl, vlines);
105 	return 1;
106 }
107 
108 /*
109  * Similar to wrap_text, but emit only o vline.
110  */
111 int
112 wrap_one(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
113 {
114 	struct vline *vl, *t;
115 
116 	/*
117 	 * be lazy: call wrap_text and then discard the continuations.
118 	 */
119 
120 	if (!wrap_text(buffer, prfx, l, width))
121 		return 0;
122 
123 	TAILQ_FOREACH_SAFE(vl, &buffer->head, vlines, t) {
124 		if (vl->flags & L_CONTINUATION) {
125 			TAILQ_REMOVE(&buffer->head, vl, vlines);
126 			free(vl->line);
127 			free(vl);
128 		}
129 	}
130 
131 	return 1;
132 }
133 
134 /*
135  * Build a list of visual line by wrapping the given line, assuming
136  * that when printed will have a leading prefix prfx.
137  */
138 int
139 wrap_text(struct buffer *buffer, const char *prfx, struct line *l, size_t width)
140 {
141 	const char	*separators = " \t-";
142 	const char	*start, *end, *line, *lastsep, *lastchar;
143 	uint32_t	 cp = 0, state = 0;
144 	size_t		 cur, prfxwidth, w;
145 	int		 flags;
146 
147 	if ((line = l->line) == NULL)
148 		return push_line(buffer, l, NULL, 0, 0);
149 
150 	prfxwidth = utf8_swidth(prfx);
151 	cur = prfxwidth;
152 	start = line;
153 	lastsep = NULL;
154 	lastchar = line;
155 	flags = 0;
156 	for (; *line; line++) {
157 		if (utf8_decode(&state, &cp, *line))
158 			continue;
159 		w = utf8_chwidth(cp);
160 		if (cur + w >= width -1) {
161 			end = lastsep == NULL
162 				? utf8_next_cp((char*)lastchar)
163 				: utf8_next_cp((char*)lastsep);
164 			if (!push_line(buffer, l, start, end - start, flags))
165 				return 0;
166 			flags = L_CONTINUATION;
167 			start = end;
168 			cur = prfxwidth + utf8_swidth_between(start, lastchar);
169 		} else if (strchr(separators, *line) != NULL) {
170 			lastsep = line;
171 		}
172 
173 		lastchar = utf8_prev_cp(line, l->line);
174 		cur += w;
175 	}
176 
177 	return push_line(buffer, l, start, line - start, flags);
178 }
179 
180 int
181 hardwrap_text(struct buffer *buffer, struct line *l, size_t width)
182 {
183 	const char	*line, *start, *lastchar;
184 	int		 cont;
185 	uint32_t	 state = 0, cp = 0;
186 	size_t		 cur, w;
187 
188 	if ((line = l->line) == NULL)
189 		return push_line(buffer, l, NULL, 0, 0);
190 
191 	start = line;
192 	lastchar = line;
193 	cont = 0;
194 	cur = 0;
195 	for (; *line; line++) {
196 		if (utf8_decode(&state, &cp, *line))
197 			continue;
198 		w = utf8_chwidth(cp);
199 		if (cur + w >= width) {
200 			if (!push_line(buffer, l, start, lastchar - start, cont))
201 				return 0;
202 			cont = 1;
203 			cur = 0;
204 			start = lastchar;
205 		}
206 
207 		lastchar = utf8_prev_cp(line, l->line);
208 		cur += w;
209 	}
210 
211 	return push_line(buffer, l, start, line - start, cont);
212 }